I've always turned off Turbo Boost on my Intel laptops anyway, because of the heat/battery hit. If I was doing something that I really wanted the extra speed and I was plugged in, I would turn it back on for that task, but I never really felt I was missing anything by having it off.
Considering how easy it is to turn on/off (on macOS at least I used Turbo Boost Switcher which added a button in the menu bar to toggle it) I don't think you would have a noticeable performance hit by keeping it off except when you need it.
Considering how easy it is to turn on/off (on macOS at least I used Turbo Boost Switcher which added a button in the menu bar to toggle it) I don't think you would have a noticeable performance hit by keeping it off except when you need it.